* libee/line.c: genericized line drawing for future use.

libee/line.c

@@ -27,15 +27,36 @@
 
 #include "ee.h"
 
+struct line
+{
+    int x1, y1;
+    int x2, y2;
+    char c;
+    void (*draw) (struct line*);
+};
+
+static void clip_line(struct line*);
 static uint8_t clip_bits(int, int);
-static void draw_solid_line(int, int, int, int, char);
+static void draw_solid_line(struct line*);
 
 void ee_draw_line(int x1, int y1, int x2, int y2, char c)
+{
+    struct line s;
+    s.x1 = x1;
+    s.y1 = y1;
+    s.x2 = x2;
+    s.y2 = y2;
+    s.c = c;
+    s.draw = draw_solid_line;
+    clip_line(&s);
+}
+
+static void clip_line(struct line* s)
 {
     uint8_t bits1, bits2;
 
-    bits1 = clip_bits(x1, y1);
-    bits2 = clip_bits(x2, y2);
+    bits1 = clip_bits(s->x1, s->y1);
+    bits2 = clip_bits(s->x2, s->y2);
 
     if(bits1 & bits2)
         return;
@@ -43,41 +64,68 @@ void ee_draw_line(int x1, int y1, int x2, int y2, char c)
     if(bits1 == 0)
     {
         if(bits2 == 0)
-            draw_solid_line(x1, y1, x2, y2, c);
+            s->draw(s);
         else
-            ee_draw_line(x2, y2, x1, y1, c);
+        {
+            int tmp;
+            tmp = s->x1; s->x1 = s->x2; s->x2 = tmp;
+            tmp = s->y1; s->y1 = s->y2; s->y2 = tmp;
+            clip_line(s);
+        }
 
         return;
     }
 
     if(bits1 & (1<<0))
     {
-        y1 = y2 - (x2-0) * (y2-y1) / (x2-x1);
-        x1 = 0;
+        s->y1 = s->y2 - (s->x2 - 0) * (s->y2 - s->y1) / (s->x2 - s->x1);
+        s->x1 = 0;
     }
     else if( bits1 & (1<<1) )
     {
         int xmax = ee_get_width() - 1;
-        y1 = y2 - (x2-xmax) * (y2-y1) / (x2-x1);
-        x1 = xmax;
+        s->y1 = s->y2 - (s->x2 - xmax) * (s->y2 - s->y1) / (s->x2 - s->x1);
+        s->x1 = xmax;
     }
     else if( bits1 & (1<<2) )
     {
-        x1 = x2 - (y2-0) * (x2-x1) / (y2-y1);
-        y1 = 0;
+        s->x1 = s->x2 - (s->y2 - 0) * (s->x2 - s->x1) / (s->y2 - s->y1);
+        s->y1 = 0;
     }
     else if( bits1 & (1<<3) )
     {
         int ymax = ee_get_height() - 1;
-        x1 = x2 - (y2-ymax) * (x2-x1) / (y2-y1);
-        y1 = ymax;
+        s->x1 = s->x2 - (s->y2 - ymax) * (s->x2 - s->x1) / (s->y2 - s->y1);
+        s->y1 = ymax;
     }
 
-    ee_draw_line(x1, y1, x2, y2, c);
+    clip_line(s);
+}
+
+static uint8_t clip_bits(int x, int y)
+{
+    uint8_t b = 0;
+
+    if(x < 0)
+        b |= (1<<0);
+    else if(x >= ee_get_width())
+        b |= (1<<1);
+
+    if(y < 0)
+        b |= (1<<2);
+    else if(y >= ee_get_height())
+        b |= (1<<3);
+
+    return b;
 }
 
-static void draw_solid_line(int x1, int y1, int x2, int y2, char c)
+static void draw_solid_line(struct line* s)
 {
+    int x1 = s->x1;
+    int y1 = s->y1;
+    int x2 = s->x2;
+    int y2 = s->y2;
+
     int dx = abs(x2-x1);
     int dy = abs(y2-y1);
 
@@ -95,7 +143,7 @@ static void draw_solid_line(int x1, int y1, int x2, int y2, char c)
         for(; dx>=0; dx--)
         {
             ee_goto(x1, y1);
-            ee_putchar(c);
+            ee_putchar(s->c);
             if(delta > 0)
             {
                 x1 += xinc;
@@ -118,7 +166,7 @@ static void draw_solid_line(int x1, int y1, int x2, int y2, char c)
         for(; dy >= 0; dy--)
         {
             ee_goto(x1, y1);
-            ee_putchar(c);
+            ee_putchar(s->c);
             if(delta > 0)
             {
                 x1 += xinc;
@@ -134,20 +182,3 @@ static void draw_solid_line(int x1, int y1, int x2, int y2, char c)
     }
 }
 
-static uint8_t clip_bits(int x, int y)
-{
-    uint8_t b = 0;
-
-    if(x < 0)
-        b |= (1<<0);
-    else if(x >= ee_get_width())
-        b |= (1<<1);
-
-    if(y < 0)
-        b |= (1<<2);
-    else if(y >= ee_get_height())
-        b |= (1<<3);
-
-    return b;
-}
-